1991 WMHB Atlantic hurricane season
The 1991 Atlantic hurricane season was a near-average season. The hurricane season officially began on June 1st and ended on November 30th. The season was slightly below-average due to a weak early-season El Nino. The season's first storm, Tropical Storm Ana, developed on July 5th and churned in the open Atlantic without any effects on land. The season's last storm, Tropical Storm Juan, dissipated on November 4th. By far the season's most notable storm was its first major hurricane, Hurricane Bob, a powerful and destructive tropical cyclone which caused $11 billion in damage (1991 USD) and 1,090 fatalities across the Caribbean islands and Central America. Bob was also the season's strongest storm with maximum sustained wind speeds of 140 mph (220 km/h) while north of Puerto Rico. Hurricane Grace was unusual in the fact that it developed from a cut-off circulation from an extratropical cyclone. As a result, the hurricane had an unusually low pressure of 969 mbar despite having wind speeds of only 80 mph. Aside from Hurricane Bob, only one other major hurricane developed in 1991, Hurricane Henri, which briefly attained wind speeds of 115 mph (185 km/h). Seasonal Summary ImageSize = width:800 height:240 PlotArea = top:10 bottom:80 right:20 left:20 Legend = columns:3 left:30 top:58 columnwidth:270 AlignBars = early DateFormat = dd/mm/yyyy Period = from:01/07/1991 till:01/12/1991 TimeAxis = orientation:horizontal ScaleMinor = grid:black unit:month increment:1 start:01/08/1991 Colors = id:canvas value:gray(0.88) id:GP value:red id:TD value:rgb(0.38,0.73,1) legend:Tropical_Depression_=_<39_mph_(0–62_km/h)_(TD) id:TS value:rgb(0,0.98,0.96) legend:Tropical_Storm_=_39–73_mph_(63–117 km/h)_(TS) id:C1 value:rgb(1,1,0.80) legend:Category_1_=_74–95_mph_(119–153_km/h)_(C1) id:C2 value:rgb(1,0.91,0.46) legend:Category_2_=_96-110_mph_(154-177_km/h) id:C3 value:rgb(1,0.76,0.25) legend:Category_3_=_111-130_mph_(178-209-km/h) id:C4 value:rgb(1,0.56,0.13) legend:Category_4_=_131-155_mph_(210-249_km/h) id:C5 value:rgb(1,0.38,0.38) legend:Category_5_=_>=156_mph_(>=250_km/h) Backgroundcolors = canvas:canvas BarData = barset:Hurricane bar:Month PlotData= barset:Hurricane width:11 align:left fontsize:S shift:(4,-4) anchor:till from:05/07/1991 till:08/07/1991 color:TS text:"Ana (TS)" from:07/08/1991 till:24/08/1991 color:C4 text:"Bob (C4)" from:12/08/1991 till:14/08/1991 color:TS text:"Claudette (TS)" from:27/08/1991 till:31/08/1991 color:TS text:"Danny (TS)" from:04/09/1991 till:11/09/1991 color:C1 text:"Erika (C1)" from:14/09/1991 till:18/09/1991 color:TS text:"Frederic (TS)" from:15/09/1991 till:17/09/1991 color:TD text:"Seven (TD)" from:22/09/1991 till:25/09/1991 color:C1 text:"Grace (C1)" barset:break from:27/09/1991 till:10/10/1991 color:C3 text:"Henri (C3)" from:02/10/1991 till:05/10/1991 color:TD text:"Ten (TD)" from:21/10/1991 till:26/10/1991 color:TS text:"Isabel (TS)" from:07/11/1991 till:15/11/1991 color:C1 text:"Juan (C1)" bar:Month width:5 align:center fontsize:S shift:(0,-20) anchor:middle color:canvas from:01/07/1991 till:01/08/1991 text:July from:01/08/1991 till:01/09/1991 text:August from:01/09/1991 till:01/10/1991 text:September from:01/10/1991 till:01/11/1991 text:October from:01/11/1991 till:01/12/1991 text:November TextData = pos:(570,30) text:"(From the" pos:(617,30) text:"Saffir-Simpson Hurricane Scale)" Systems Tropical Storm Ana On July 3rd, a tropical wave exited the coast of Africa. Under marginally favorable conditions, the wave developed into the season's first tropical depression two days later. Conditions gradually became more favorable for development as the depression tracked westwards, and on July 6th it strengthened into Tropical Storm Ana. However, light wind shear hindered further strengthening of the storm, and Ana weakened back to a tropical depression at 2:00 UTC the next day. On July 8th, strong wind shear, caused by a weak El Nino, became much more unfavorable for sustainment of a tropical storm, and Ana began to rapidly weaken shortly after restrengthening into a tropical storm. At 17:00 UTC, a reconnaissance flight into a weakening Ana confirmed that it had weakened into a disorganized tropical wave, and advisories were discontinued an hour later before Ana dissipated over the open Atlantic at 23:00 UTC the same day. Hurricane Bob After over a month of inactivity, conditions in the Atlantic basin became more favorable as the El Nino began to dissipate. On August 7th, Tropical Depression Two formed over the Atlantic Ocean from a strong and well-organized tropical wave. By 16:00 UTC that day, the tropical depression had strengthened into Tropical Storm Bob. Possessing a large wind field for a tropical storm, Bob began to steadily intensify under favorable conditions fueled by warm ocean waters, becoming the 1991 season's first hurricane on August 9th. Shortly after being upgraded to a hurricane, Bob began to rapidly intensify as it tracked west-southwest towards the Caribbean islands. By August 10th, Bob had become a Category 3 major hurricane, increasing its wind speeds from 80 mph to 120 mph in just 20 hours. The storm's wind field had also grown large, possessing a hurricane-force wind field of 180 miles and a tropical storm-force wind field of 580 miles. Bob's wind field continued to expand as the hurricane reached Category 4 intensity early on August 11th, reaching peak intensity north of Puerto Rico at 5:00 UTC. Bob's tropical storm-force wind field had grown to a massive 625 miles in diameter as it made landfall on Hispaniola with wind speeds of 130 mph (215 km/h). Torrential rainfall triggered severe flooding and mudslides that took the lives of at least 597 people as well as causing $2.4 billion in damages, making Bob one of the worst natural disasters ever to strike the island. From there, Bob continued westward to strike Cuba on August 18th as a Category 3 hurricane, causing a further 142 fatalities and $3 billion in damages from flooding and landslides. Bob continued to slowly track westwards towards the Yucatan Peninsula, making landfall in Belize on August 20th with wind speeds of 105 mph (165 km/h). The large size of the storm allowed heavy rainfall to cause deadly mudslides in Honduras and Guatemala, which caused 351 fatalities in total. Damage was very severe to Belize and Mexico, at $5.6 billion USD in damages estimated. Bob then began to rapidly weaken over the mountainous terrain of Central America, becoming a tropical storm as it briefly passed offshore into the Bay of Campeche. On August 24th, Bob finally dissipated over the Mexican state of Guerrero after persisting as a weak tropical depression for nearly 4 days. With an estimated $11 billion (1991 USD) in total damages, Bob was, at the time, the costliest Atlantic hurricane on record until it was surpassed by Hurricane Opal in 1995. Tropical Storm Claudette A tropical wave merged with a surface trough over the Gulf of Mexico on August 11th to produce a small area of disturbed weather. This disturbance quickly organized and became Tropical Depression Three on August 12th while off the coast of Texas. Strengthening continued as the system curved southeast, becoming Tropical Storm Claudette at 12:00 UTC the next day. The storm continued to strengthen as it curved back to the north, reaching peak intensity at 20:00 UTC with wind speeds of 60 mph (95 km/h). On August 14th, Claudette made landfall just east of New Orleans, LA at peak intensity. Up to 22 inches of rain fell in parts of the state, and coastal flooding caused $26 million in damages, primarily due to uninsured homeowners having their homes flooded. 2 deaths were linked to the storm's passage through the states as Claudette rapidly weakened over land. At 20:00 EST, Claudette dissipated over northern Mississippi. Tropical Storm Danny A large area of disturbed weather persisted over Hispaniola on August 26th, bringing heavy rains to the area. The disturbance developed a circulation while east of the Bahamas, and on August 27th seemed to resemble a subtropical cyclone. The system was accordingly classified as a subtropical depression at 10:00 UTC that day as it was tracking northwest towards the Carolinas. At 16:00 UTC the subtropical depression transitioned into a fully tropical storm, being named Danny while located around 280 miles southeast of Georgia. Approaching the Carolinas at 13 mph, Danny curved to the northeast away from shore, although strong rip currents generated by the storm resulted in 74 rescues across the United States east coast by the US Coast Guard. Danny reached peak intensity at around 8:00 EST on August 29th as it accelerated towards Canada. Danny stayed a tropical cyclone for almost 2 more days until finally transitioning to an extratropical storm at 7:00 UTC while around 235 miles south of Halifax, Nova Scotia. Hurricane Erika A tropical wave exited the coast of Africa on September 2nd. Conditions gradually became more conducive for development, and a tropical depression formed two days later. Gradual strengthening occurred thereafter, and the depression became Tropical Storm Erika on August 5th. Initially, the storm moved at a fast pace but slowed as it began to intensify and approach the Caribbean Sea. On August 6th, Erika strengthened into a hurricane just before landfall in Anguilla. Damage was relatively minor, although at least 7 people were killed and $4 million in damages was caused as Erika proceeded west, taking a glancing blow at the Virgin Islands just before weakening back to a tropical storm. Erika continued to track relatively slowly through the Caribbean as it slowly weakened. On August 10th, Erika began to restrengthen, but shortly thereafter again began to weaken. At 21:00 UTC Erika weakened to a tropical depression, and by the next day had degenerated to a remnant low while around 260 miles off the Floridan coast. Over its week-long lifespan, Erika caused 9 fatalities and $5 million (1991 USD) in damages. Tropical Storm Frederic On September 14th, Tropical Depression Six formed from a strong and vigorous tropical wave in the tropical Atlantic Ocean. Moving west-northwestward, the depression quickly strengthened to become Tropical Storm Frederic at 14:00 UTC. Continuing its northwesterly track, further strengthening of the system occurred at a much slower pace. The storm reached peak intensity on September 17th. Frederic's forward movement slowed drastically to 3 mph as it approached the Lesser Antilles. On September 17th, Frederic passed over the Grenadines as a minimal tropical storm, bringing large amounts of rain to the area and causing no damage or fatalities. Hours later, Frederic weakened to a tropical depression as it entered the Caribbean Sea. On September 18th, a reconnaissance flight reported that Frederic had degenerated to an open wave, and advisories were discontinued at 20:00 UTC. Just before midnight, the remnant circulation of Frederic dissipated over the southern Caribbean Sea. The storm caused no damage or fatalities at any point of its lifetime. Tropical Depression Seven Shortly after the formation of Tropical Depression Six, another tropical wave began to organize over the Atlantic Ocean. By 19:00 UTC on September 15th, Tropical Depression Seven formed from the wave and began to strengthen. However, mild wind shear inhibited the system's development, and the depression failed to strengthen further. Although wind shear had dissipated by September 16th, the depression remained unorganized, and by 17:00 UTC had opened up into a tropical wave. The remnants, however, remained convective, and redevelopment was considered. However, the remnants failed to intensify any further and they finally dissipated at 6:00 UTC the next day. Hurricane Grace On September 21st, a low-pressure circulation detached from a powerful extratropical cyclone over the northern Atlantic. The low drifted south and gradually acquired subtropical characteristics, although was classified as an extratropical cyclone. Unusually, a small tropical cyclone was found at the system's center, presumably formed from unusually warm ocean waters. On September 22nd, the small tropical system was classified as Tropical Storm Grace. On September 23rd, a flight into the system found an eye feature forming and wind speeds of 75 mph (120 km/h), and so Grace was upgraded to a hurricane. At 18:00 EST, Grace reached its peak intensity while around 380 miles south of Nova Scotia with wind speeds of 80 mph (130 km/h). Thereafter, the storm began to accelerate northward towards Nova Scotia. However, Grace became an extratropical cyclone just before landfall 165 miles west of Halifax, NS. Wind gusts of hurricane-force caused thousands of power outages across Nova Scotia as Grace's extratropical remnants passed over the peninsula. On September 25th, the remnant of Grace was absorbed by a larger extratropical system while moving rapidly over the Gulf of Saint Lawrence. Hurricane Henri On September 27th, a tropical wave in the central Caribbean Sea began to organize and intensify. By 22:00 UTC it had become Tropical Depression Nine. The depression quickly strengthened into Tropical Storm Henri 5 hours later as it slowly tracked northwest. On September 29th, Henri began to undergo rapid intensification, becoming a hurricane at 12:00 UTC. From there, Henri continued to rapidly intensify with its wind speeds increasing from 80 mph (130 km/h) to 110 mph (175 km/h) in just 4 hours. With a well-defined eye and structure, Henri briefly intensified into a Category 3 hurricane, peaking at 115 mph (185 km/h). However, the storm weakened hours later as it approached Florida. On October 1st, Henri made landfall in St. Petersburg, FL as a Category 1 hurricane. Heavy rain and high surf caused severe coastal flooding that caused $200 million (1991 USD) in damages. No fatalities were reported, although several injuries affected surfers who attempted to surf before the storm's arrival. Henri weakened rapidly into a tropical storm as it crossed the state of Florida, causing river flooding and spawning several tornadoes, adding an additional $20 million to the damage total. The storm turned northeast as it headed out to sea, briefly re-intensifying to become a hurricane again on October 4th. However, Henri began to weaken yet again as it moved over cooler waters, remaining a tropical cyclone for 5 more days until becoming extratropical south of Nova Scotia and finally dissipating on October 10th. In total, Henri was responsible for $220 million in damages and 2 fatalities, both of which occurred in Mexico as the storm passed close by. Tropical Depression Ten A large, yet disorganized tropical wave passed north of the Leeward Islands on September 30th. The wave began to organize later the next day and continued strengthening until it became the season's tenth tropical depression on October 2nd. A large and somewhat disorganized system, Tropical Depression Ten brought rains to the Greater Antilles as it tracked through the Atlantic Ocean, remaining just north of the islands. The depression remained disorganized but large as it crossed over the Bahamas on October 3rd, bringing heavy rainfall. Winds gusted to tropical storm-force as the depression tracked west towards the state of Florida. Interaction with Tropical Storm Henri to the north caused Ten to weaken significantly and become very disorganized. It no longer qualified as a tropical cyclone by October 5th, and the NHC downgraded it to a remnant low at 20:00 UTC that night. Tropical Storm Isabel On October 19th, a tropical wave merged with an elongated surface trough to produce a strong area of low pressure. Tracking north, the low began to strengthen and acquire more tropical characteristics, and on October 21st was well-organized enough to be classified as Tropical Depression Eleven. Strengthening was slow to occur as the depression tracked northwest, but at 1:00 UTC on October 23rd a large burst in convection and reports of tropical storm-force winds allowed the NHC to classify the system as Tropical Storm Isabel. Isabel tracked slowly northwest towards Cuba as it gradually, but very slowly, strengthened. On October 24th, Isabel made landfall in eastern Cuba, bringing heavy rainfall that triggered mudslides in the central region of the island, although in rural areas. Rainfall was generally beneficial to the growing season, although several thousand square feet of farmland in villages in Cuba's mountainous areas was ruined by mudslides. Nevertheless, no fatalities occurred and damage was minimal as Isabel left the island for the Atlantic Ocean. Shortly thereafter, strong wind shear created an unfavorable environment for tropical cyclone development, and Isabel began to rapidly weaken until it degenerated to a remnant area of disturbed weather before dissipating on October 26th. Hurricane Juan A front that had moved off the east coast of the United States began to acquire subtropical characteristics as its circulation entered the warm waters of the Gulf Stream. The system was designated as Subtropical Storm One on November 7th after the storm produced a wind gust of 65 mph (100 km/h). Despite its appearance resembling that of a frontal boundary or low, the subtropical storm became a fully tropical system on November 9th while passing well off the shore of North Carolina, and it was reclassified as Hurricane Juan after the Hurricane Hunters found hurricane-force winds in the large system. Juan posed no threat to land as it tracked northeast. Although its circulation remained well-organized, Juan did not strengthen past 75 mph (120 km/h) and reached peak intensity off the coast of New Jersey on November 10th. Thereafter, Juan began to weaken over the cool waters of the northern Atlantic. The storm's outer rainbands brought showers to New England and Atlantic Canada. Juan remained a strong tropical storm at a high latitude before finally becoming a strong extratropical storm 325 miles east of Newfoundland. The extratropical remnant of Juan continued to race northeast towards the Arctic, producing hurricane-force wind gusts in southern Greenland before finally dissipating over the far northern Atlantic Ocean on November 15th. Storm Names The following names were used for tropical cyclones that formed in the Atlantic during 1991. This list is the same list used in 1985 with the exceptions of Danny and Erika, which replaced David and Elena, respectively, after they caused extensive damage in the Caribbean and the United States. Storms were named Danny and Erika for the first time in 1991 due to David and Elena being retired after the 1985 season. Retirement In the spring of 1992, the World Meteorological Association retired the name Bob from the list above due to its devastating impacts in the Caribbean and Central America. It was replaced by Bill for the 1997 Atlantic hurricane season. Category:Past Hurricane Seasons Category:Past Tropical Cyclone Seasons Category:Past Tropical Cyclone Season Category:WMHB seasons (Cooper) Category:WMHB Seasons (Cooper) Category:What-might-have-been seasons